The present invention relates to an electrical connector comprising a plate-like base, a resilient contact arm extending from the base and having a contact portion in contact with a circuit board at its free end, and a plurality of contacts each having a connection portion extending from the base and connected to a separate circuit board from said circuit board.
A conventional electrical connector according to the prior art is shown in FIGS. 5(A) and 5(B). This electrical connector 101 has a plurality of contacts 110 and an insulative housing 120 that accommodates these contacts 110.
Each of the stamped contacts 110 has a plate-like base 111. A resilient contact arm 112 extends from the base 111 on the right side in a horizontal direction (the right side in FIG. 5 (B)). A contact portion 113 is provided on the contact arm 112, the contact portion makes contact with a circuit board (not shown) at its free end. A connection portion 114 extends from the base 111 on the left side and is soldered to a second circuit board (not shown). A contact press-fit portion 115 extends upward at an upper end of the base 111 between the resilient contact arm 112 and the connection portion 114.
A plurality of contact accommodating passageways 121 in which the contacts 110 are accommodated are provided in the housing 120 in parallel to each other at a predetermined pitch in a transverse direction (a vertical direction in FIG. 5 (A)). Each contact accommodating passageway 121 is open at the lower side and has an upper wall which extends across most of the upper side. A press-fit opening 122 into which the contact press-fit portion 115 is press-fitted and a slit 123 from which the contact portion 113 projects are provided in this upper wall. The press-fit opening 122 and the slit 123 are alternately provided in the transverse direction of the housing 120, as shown in FIG. 5(A).
When the contact press-fit portion 115 of each contact 110 is fully inserted and press-fit into the press-fit opening 122 of the housing 120, the contact portion 113 passes through the slit 123. The plurality of contacts 110 are thereby secured to the housing 120 to complete an electrical connector 101. The connection portion 114 of this completed electrical connector 101 is soldered on the second circuit board to mount the electrical connector 101 on the second circuit board. The first circuit board is positioned on the connector so that circuit paths of the circuit board make contact with the contact portions 113 of the electrical connector 101. The first circuit board is maintained in position relative to the second circuit board by a fixing means such as screws. The two circuit boards are electrically connected to each other by means of the connector 101.
However, when the first circuit board engages the contact portions 113, each contact portion 113 makes contact with a respective circuit path of the circuit board. As the electrical engagement is made at a single point, the contact reliability of each resilient contact arm 112 with a respective circuit path of the circuit board is low. Thus, if the first circuit board is warped, the contact portion 113 and circuit path may not be placed in electrical engagement even when the two circuit boards are fastened to each other by a fixing means such as screws.
Also, since the contact press-fit portion 115 extends upward at an upper end of the base 111 of the contact 110 between the resilient contact arm 112 and the connection portion 114, an arm length of the resilient contact arm 112 is limited. Thus, a resilient region of the resilient contact arm 112 is small and consequently the resilient contact arm 112 may be plastically deformed even if a displacement of the contact portion 113 is small.
The present invention is made in view of the above problems, and an object is to provide an electrical connector which has a plurality of contacts having improved contact reliability of a contact arm portion with a circuit board.
Another object of the present invention is to provide an electrical connector which has a plurality of contacts having an increased arm length of a contact arm portion a horizontal direction of the housing.
The electrical connector has a plate-like base. A contact arm portion extends from the base and has a contact portion in contact with a first circuit board at its free end. A plurality of contacts, each having a connection portion, extend from the base and connect to a second separate circuit board. Each contact is formed by stamping a metal plate. An insulative housing accommodates the contacts and has in its upper wall a slit from which the contact portion projects. The contact arm portion is composed of first and second resilient contact arms having the contact portion at their respective free ends and extending in parallel to each other substantially obliquely in a horizontal direction of the base. The starting positions of said first and second resilient contact arms are spaced in horizontal and vertical directions.
The resilient contact arm has first and second resilient contact arms with the contact portion positioned at their respective free ends. The contact portions extend in parallel to each other substantially obliquely in a horizontal direction of the base so that the circuit board makes contact with the contact portions of the first and second resilient contact arms. The first and second resilient contact arms are flexible independently from the electrical connector, thereby offering improved contact reliability of the resilient contact arms with the circuit board.
The first and second resilient contact arms extend in parallel to each other substantially obliquely from one end toward the other end in a horizontal direction of the base. The positions of the starting points or unstressed positions of the first and second resilient contact arms are shifted or spaced in horizontal and vertical directions, thereby allowing for an increased arm length of the two resilient contact arms along a horizontal direction of the housing.
If a horizontal length of the housing is fixed while the positions of the starting points of the first and second resilient contact arms are spaced only in a horizontal direction, then the distance between the two resilient contact arms is not sufficient to allow for clearance between the two resilient contact arms during stamping of a metal plate. Thus, by spacing the positions of the starting points of the first and second resilient contact arms not only in a horizontal direction but also in a vertical direction, a sufficient clearance is provided between the two resilient contact arms during stamping of a metal plate.
The position of the starting point of the first resilient contact arm is downwardly offset with respect to the position of the starting point of said second resilient contact arm positioned. A vertical length of the contact portion of the first resilient contact arm is longer than a vertical length of the contact portion of the second resilient contact arm.
This electrical connector ensures that the contact portions of the first and second resilient contact arms make contact with the circuit board without making a horizontal dimension of the housing excessive.
The housing has on an upper portion of its side wall, a second slit communicating with the slit formed in said upper wall. The contact portion of the first resilient contact arm enters the second slit when the first resilient contact arm is flexed downward.
When the first resilient contact arm having the vertically long contact portion is flexed downward, the contact portion enters the second slit, avoiding any collision of the contact portion of the first resilient contact arm with the side wall of the housing, thereby allowing a horizontal dimension of the housing to be utilized effectively. Also, when the first resilient contact arm is flexed downward, the contact portion is guided by the second slit, avoiding any damage to the first resilient contact arm due to the disengagement of the contact portion from the second slit.